The invention relates to removal of residual chromium from commercially produced polyvinyl chloride (PVC) membranes and films. This is important because occupation health professionals use this PVC film in disc form for the monitoring and analysis of hexavalent chromium and total chromium present in workplace environments Chromium metals and hexavalent chromium are known health hazards that need to be monitored in workplace environments. However, if chromium background is present in the filters, the interpretation of the results can be problematic. Thus, it would be desirable to remove the background concentration of chromium metals and hexavalent chromium that often times interferes with the analytical analysis methods ability to discern environmentally harvested chromium materials from PVC filter manufacturing byproducts.
M. R. Baloga and J. E. Earley, The Kinetics of the Oxidation of Cr (III) to Cr (VI) by Hydrogen Peroxide, J. Am. Chem. Soc. 83 4906-4909 (1961) observed that Cr (III) can be oxidized to Cr (VI) with hydrogen peroxide under alkaline conditions. Since that time other authors have examined the kinetics of the reaction. Additional literature illustrates pathways where Cr (VI) is reduced to Cr (III) under acidic conditions. Furthermore, there have been studies that have illustrated the effect of small organic molecules effect on the kinetics of the reaction. Additional articles examine the mechanism in the presence of small organic molecules.
However, there have been no previous references that describe the reaction under the influence of an organic polymer. Furthermore, as discussed above, previous literature indicates that the oxidation of Cr (III) to Cr (VI) requires alkaline modification of the solution. This alkaline modification can cause structural damage to the PVC filters and make them unsuitable for use.
A need exists for a non-destructive method of removing the background concentration of chromium metals and hexavalent chromium that is present in the PVC filters.